536 W. WOODLAND. 
histological elements contained within the same body-wall. 
In both C. sp. and C. brunnea the spicules may be 
primarily classified into (1) the very small superficial spicules, 
situated in the outermost layer of the body-wall or epistroma, 
and (2) the much larger perforated-plate spicules situated in 
the deeper layers of the stroma. In both species the small 
superficial spicules are either triradiate (fig. 39 h) or X-shaped 
(fig. 40) in ground plan, and the plane of the three or four 
rays, as the case may be, is, as in the case of all other 
Cucumarian spicules, parallel with the plane of the body- 
wall. The principal features of these superficial or epistromal 
spicules consists in the fact that the extremities of the three 
or four rays cur] outwards, i.e. towards the exterior of the 
animal, and either branch irregularly ending in knobs (figs. 
40, 41) or join peripherally into a ring (after the style of the 
Auricularian wheel) which bears knobs on its external edge 
(fig. 42). With respect to the more deeply situated plate 
spicules, these differ somewhat in the two species. In C. 
sp.! (of which species I have by far the greater number 
of specimens) the plate spicules, which are densely crowded, 
sending my slides to the Plymouth Marine Biological Laboratory for identifi- 
cation, Mr. Pace, who has recently been investigating the Cucumariide 
obtained at Plymouth, replied that he was unable to say what species it was, 
owing to the parts of the body-wall not being separate from each other, and 
that, so far as he could ascertain, it was a new species to him. Seeing, how- 
ever, that many of the spicules are nodulated and are present in great 
numbers, C. sp. (originally forwarded to me as C. pentactes) is probably 
C. Normani (‘* Note on Two Species of Cucumaria from Plymouth, 
etc.,” by S. Pace, ‘Journ. Mariue Biol. Assoc.,’ n. s., vol. vii, part 2, 1904), 
not C. saxicola, which contains no nodulated spicules. However, the 
question of the identity of species is fortunately of little importance to me, 
since the process of spicule-formation is identical in all the species named; 
all I can definitely state on the subject is that I received specimens of 
Cucumaria presenting the two quite distinct sets of spicules I have 
enumerated in the text. IJ wish to thank Mr. Pace for kindly attempting 
to identify the specific nature of my specimens. 
1 It must be borne in mind that this enumeration of the several kinds of 
spicules only applies to young specimens of Cucumaria, not more than 8 mm, 
in length. 
